Device for recording the parameters of an aerosol in particular in inhalation therapy devices

ABSTRACT

The invention relates to a device for detecting the parameters of an aerosol, in particular in inhalation therapy devices, whereby light is shone through a translucent material but not through a transparent material in a detection region and is detected and analysed by means of two receivers.

The invention relates to a device for recording the parameters of anaerosol, in particular in inhalation therapy devices.

Known from DE 100 22 795 A is a breath-controlled inhalation therapydevice, in which an infrared light transmitter is disposed adjacent toan infrared light receiver in an opening in the mouthpiece of thetherapy device such that the infrared light emitted by the transmitterarrives in a detection area in which a still aerosol is located. Theinfrared light is reflected by the aerosol particles or droplets andarrives at the receiver which emits an output signal that corresponds tothe density of the aerosol. The transparent surface through which theinfrared light is emitted and the reflected infrared light is receivedis disposed in the interior of the therapy device, i.e., for example, inthe internal space of the mouthpiece, so that in the known inhalationtherapy device, the light shining in can directly arrive at the aerosoldroplets from the transmitter and the light reflected by these dropletscan arrive at the receiver. The transmitter and receiver work withoptical-imaging radiation.

Although the known device is basically suitable for ensuringbreath-controlled nebulisation, and although the control methoddescribed in DE 100 22 795 A can be reliably realised, it has shown thatowing to the adhesion of larger and smaller droplets to the transparentsurface through which the light passes, the analysis of the outputsignal of the receiver during the control process is comparativelycomplicated, in particular if the precision desired for therapeuticapplications is supposed to be achieved.

There is therefore demand for an inhalation therapy device in whichdetection of aerosol particles or droplets in a given spatial area inthe therapy device occurs in a manner that allows an analysis, inparticular control of nebulisation, to be designed more simply and thusmore economically.

In view of the above, it is the object of the invention to specify adevice for recording the parameters of an aerosol and, in particular, aninhalation therapy device having such a device, in which the analysis ofdetection signals and the control of nebulisation based thereon issimplified.

This aim is achieved by means of a device having the features describedin patent claim 1. Advantageous embodiments can be seen in thesub-claims.

It is an important factor of the invention that shining in, for exampleof light into the detection area, occurs through a translucent materialand not through a transparent material. The beam expansion linkedtherewith leads to a surprisingly high insensitivity to aerosolparticles or droplets that adhere to the material through which shiningoccurs, without the analysability of the measurement signals beingaffected. This considerable insensitivity to impaction is based on anaveraging over large spatial areas that is linked with the beamexpansion. According to the invention, the transmitter and receiver workwith non-imaging radiation.

If shining in occurs in a clocked manner or intermittently, the effectof ambient light can be determined using a reference measurement in thedark phases and can be later consulted when analysing the measurementsignals in the light phases. The reaction speed of detection is therebydetermined by means of the clock frequency.

Since at least two receivers are provided according to the invention,the output signals of the receivers could be mathematically linked inthe analysis, for example by forming a quotient, whereby reducing theeffect of ambient light and/or temperature fluctuations. It isadvantageous in this regard for one receiver to be disposed in the mainbeam direction of the transmitter and for the other to be disposedsubstantially perpendicularly to the main beam direction.

Reduction of the effect of ambient light can also occur by means ofseries-connected long-pass filters, preferably on the receivers.

In the following description of embodiments, the invention is explainedin more detail by means of the figures.

FIG. 1 shows an inhalation therapy device having a recording deviceaccording to the invention,

FIG. 2 shows a view of the arrangement of the transmitter and receiversof a recording device according to the invention, and

FIG. 3 shows a further inhalation therapy device having a recordingdevice according to the invention.

A general view of an embodiment of an inhalation therapy deviceaccording to the invention is shown in FIG. 1. In this embodiment, theinhalation therapy device comprises a nebuliser 1 that accommodates anebuliser nozzle 40 in its interior, which acts as the primary aerosolgenerator. The nebuliser nozzle 40 is supplied with compressed air by acompressor 2 via a tube 3 when the compressor is switched on. Thenebuliser nozzle then sucks in the liquid to be nebulised from a storagecontainer 41 in which it is disposed. The compressor can be manuallyswitched on via a rocker switch 4. A mouthpiece 5 is attached to thenebuliser 1, via which a patient inhales the aerosol generated in thenebuliser by the nebuliser nozzle.

Alternatively, an inhalation therapy device having a membrane nebuliser52 can also be used instead of the inhalation therapy device with anebuliser nozzle; such an inhalation therapy device is exemplified inFIG. 3. In order to generate the aerosol, the inhalation therapy device1 according to FIG. 3 comprises a membrane nebuliser 52 having amembrane 53 attached in a ring shape to a piezo element 54. The liquid55 to be nebulised is contiguous with a membrane 53 and is nebulisedthrough the openings of said membrane 53 when the piezo element 54causes the membrane to oscillate. The piezo element 54 is activated forthis purpose by means of an excitation device 56. The inhalation therapydevice 1 shown in FIG. 2 also comprises a mouthpiece 5, via which thepatient inhales the aerosol generated by the membrane nebuliser.

As shown in FIG. 1, a transmitting means 7, a first receiving means 8and a second receiving means 9 are disposed, according to the invention,on the mouthpiece 5. Owing to the spatial arrangement of thetransmitting means and the two receiving means, an area is defined inthe interior of the mouthpiece, in which the parameters of an aerosolthat rests here can be recorded by the transmitter/receiver arrangement.This area is referred to as aerosol resting area A in this descriptionof an embodiment of the invention.

The transmitting means 7 emits light, preferably infrared light (oranother suitable radiation), into the interior of the mouthpiece 5,namely into the aerosol resting area. The first receiving means 8receives the proportion of light that penetrates the mouthpiece 5essentially unscattered and releases a first output signal I_(T) whichis supplied to an analysis/control unit 10. The first receiving means 8is arranged, for example, in the main beam direction of the transmittingmeans 7. The second receiving means 9 receives the proportion of lightthat is scattered by aerosol particles or droplets and releases a secondoutput signal I_(S) which is also supplied to the analysis/control means10. The second receiving means 9 is arranged, for example, at an angle,preferably perpendicularly to the main beam direction of thetransmitting means 7.

A cross-section through the mouthpiece 5 of the embodiment of aninhalation therapy device according to the invention as seen in FIG. 1is shown in FIG. 2.

It can be seen in FIG. 2 how the transmitting means 7 is arranged on thewall of the mouthpiece 5 such that the transmitting means 7 emits lightinto the interior of the mouthpiece 5 through the first translucent wallsection 13. In this case, which is particularly economical, the exitsurface on the transmitter for the emitted radiation can be as desired.If the mouthpiece is made of a transparent material, the transmittingmeans 7 is provided with a translucent surface, through which theradiation of the transmitting means 7 passes and which assumes thefunction of the first translucent wall section 13. If the mouthpiece ismade of a non-transparent material, the translucent surface of thetransmitting means 7 is arranged in an opening in the wall of themouthpiece, which is preferably completely closed by the transmittingmeans. According to the invention, the aerosol resting area, labelled Ain FIG. 2, thus achieves non-imaging radiation since the light of thetransmitter is guided through a translucent material, for example anopaline plastic.

It can furthermore be seen in FIG. 2, how the first receiving means 8 isarranged on the wall of the mouthpiece 5 such that said first receivingmeans 8 primarily receives, through a second wall section 14 of themouthpiece 5, the proportion of the light emitted into the aerosolresting area A, which comes from the transmitting means 7 and passesthrough the aerosol resting area A, i.e. in this case the interior ofthe mouthpiece 5, in an unscattered manner. This light is calledtransmission light TL in this description. If no aerosol is present inthe interior of the mouthpiece 5, the light emitted by the transmittingmeans 7 reaches the first receiving means 8 practically uninterrupted,said receiving means 8 thereupon emitting a high output signal I_(TL).As the aerosol density in the aerosol resting area A increases, thelight emitted by the transmitting means 7 will be scattered to a greaterextent such that less light reaches the first receiving means 8. Theoutput signal I_(TL) of the first receiving means 8 decreases as theaerosol density in the aerosol resting area increases.

It is less important for the arrangement of the first receiving means 8on the mouthpiece 5 whether the mouthpiece is produced from atransparent or translucent material. However, the light preferably fallsthrough a translucent material into the first receiving means 8.Reference is made in this regard to the explanations regarding thetransmitting means 7 and the first wall section 13, which accordinglyalso apply to the first receiving means 8 and the second wall section14. Particularly economical is again a mouthpiece 5 that is made of atranslucent material, which renders a further translucent material onthe first receiving means 8 unnecessary.

Finally, it can be seen in FIG. 2 how the second receiving means 9 isarranged on a third wall section 15 of the mouthpiece 5 such that saidsecond receiving means 9 primarily receives, through the second wallsection 15, the proportion of light emitted into the aerosol restingarea A, which comes from the transmitting means 7 and is scattered bythe aerosol particles or droplets. This light is called scattered lightSL in this description. If no aerosol is present in the aerosol restingarea A, i.e. in the interior of the mouthpiece 5 in the embodimentdescribed here, only a small amount of the light emitted by thetransmitting means 7 reaches the second receiving means 9; the secondreceiving means 9 thereupon emits a low output signal I_(SL). Since thelight emitted by the transmitting means 7 is scattered to a greaterextent as the aerosol density in the aerosol resting area A increases,increasingly more light reaches the second receiving means 9. The outputsignal I_(SL) of the second receiving means 9 increases as the aerosoldensity in the aerosol resting area increases.

It is less important for the arrangement of the second receiving means 9on the mouthpiece 5 whether the mouthpiece is produced from atransparent or translucent material. However, the light preferably fallsthrough a translucent material into the second receiving means 9.Reference is made in this regard to the explanations regarding thetransmitting means 7 and the first wall section 13, which accordinglyalso apply to the second receiving means 9 and the second wall section15. Particularly economical is again a mouthpiece 5 that is made of atranslucent material, which renders a further translucent material onthe second receiving means 9 unnecessary.

The first and second output signals (I_(TL), I_(SL)) of the receivingmeans 8 and 9 are supplied to the control means 10, which analyses thefirst and second output signals (I_(TL), I_(SL)) to determine theparameters of an aerosol in the aerosol resting area A.

A first analysis can occur to the effect that the control means 10determines whether or not an aerosol is present in the aerosol restingarea A. A high first output signal I_(TL) and a low second output signalI_(SL) indicate that almost no aerosol is present in the aerosol restingarea A. A low first output signal I_(TL) and a high second output signalI_(SL) indicate that an aerosol is present in the aerosol resting areaA. Therefore, the presence of the aerosol in the aerosol resting area Acan be determined as a first parameter of said aerosol.

If the second output signal I_(SL) increases and the first output signalI_(TL) decreases, this indicates that an aerosol is present in theaerosol resting area A whose density is increasing. If the first outputsignal I_(TL) increases and the second output signal I_(SL) decreases,this indicates that an aerosol is present in the aerosol resting area Awhose density is decreasing. Therefore, the change in the density of theaerosol in the aerosol resting area A can be determined as a secondparameter of said aerosol.

If calibration is carried out, the aerosol density is also to beabsolutely determined as a third parameter from the output signalsI_(SL) and I_(SL).

The control method described in DE 100 22 795 A can essentially also becarried out based on the two output signals I_(SL) and I_(SL).Particularly suitable in this regard is an inhalation therapy devicehaving a membrane nebuliser, as shown, for example, in FIG. 3. In orderto control nebulisation, the control means 10 is connected with thecompressor 2 and with the excitation device 56.

For this purpose, the quotientQ _(A) =I _(SL) /I _(TL)is preferably formed from the first and second output signals I_(SL) andI_(SL) in the control means 10. The effect of ambient light andtemperature fluctuations on the transmitting and receiving means 7, 8and 9 is thereby eliminated, or is at least clearly reduced.

For example, the presence of aerosol in the aerosol resting area Adefined by the transmitting and receiving means can be determined inthat the control means 10 determines whether the quotient is above athreshold Q_(Amin), which is only exceeded if a sufficient amount ofaerosol particles or droplets are present in the mouthpiece 5 betweenthe transmitter 7 and the receivers 8, 9.

To further improve insensitivity to ambient light, the transmittingmeans 7 is intermittently operated by the control means 10 such thatfirst time periods Z1, in which the transmitting means 7 emits lightinto the aerosol resting area A, alternate with second time periods Z2,in which the transmitter means 7 does not emit any light. The outputsignals of the first and second receiving means 8 and 9 are different inboth time periods.

In one of the second time periods Z2, in which no light is emitted intothe aerosol resting area A by the transmitting means 7, only ambientlight reaches the first and second receiving means 8 and 9, whichshines, for example, through the translucent material of the mouthpiece5 or the mouthpiece opening into the aerosol resting area A and arrivesat the first or second receiving means 8 and 9. In one of the first timeperiods Z1, in which the transmitting means 7 emits light into theaerosol resting area A, transmission light TL and scattered light SL inaddition to ambient light also reach the first and second receivingmeans 8 and 9. The output signal of the first and second receiving means8 and 9 thus changes at least as regards how high it is. The outputsignals I_(TL) and I_(SL) in the time periods Z1 and Z2 can be detectedby the control means 10 and can be allocated to time periods Z1 and Z2since the control means 10 determines the sequence of the time periodsvia activation of the transmitting means 7.

When the transmitting means 7 is operated intermittently, it is possibleto determine, in the second time periods Z2 in which the transmittingmeans 7 does not emit any light into the aerosol resting area A, theproportion of ambient light contained in the output signal of the firstand second receiving means 8 and 9. The output signals I_(TLU) andI_(SLU) occurring in the second time periods Z2 are attributed to theambient light that reaches the receivers. The control means 10 takesinto account the proportions of the output signals I_(TLU) and I_(SLU)attributed to the ambient light in the first time periods Z1, in whichthe transmitting means 7 emits light into the aerosol resting area A, inorder to eliminate the proportion of ambient light in the output signalsI_(TL) and I_(SL), for example in a manner in which the differences(I_(TL)−I_(TLU)) and (I_(SL)−I_(SLU)) are formed. The effect of ambientlight is further reduced in this manner. In this case,$Q_{A} = \frac{\left( {I_{SL} - I_{SLU}} \right)}{\left( {I_{TL} - I_{TLU}} \right)}$is formed as the quotient. It is thereby ensured, owing to the repeatedsuccession of the first and second time periods Z1 and Z2, thatfluctuations in ambient light are also taken into consideration.

The intermittent operation of the transmitting means 7 furthermore makesit possible to check the operability of the transmitting means 7 and thereceiving means 8 and 9 since alternating the operating state of thetransmitting means 7 must lead to a change in the output signal of thereceiving means. If there is no change, a defect in the transmitter orin one of the receivers can be concluded.

1. A device for detecting the parameters of an aerosol, in particular inan inhalation therapy device, comprising a. a transmitting means i.which is disposed on a body that at least partially surrounds an aerosolresting area, and ii. which emits radiation into said aerosol restingarea through a translucent material; b. a first receiving means, i.which is disposed on the body (that at least partially surrounds saidaerosol resting area, ii. which is disposed in relation to saidtransmitting means so as to primarily receive transmission radiation,and iii. which emits a first analysis signal that corresponds to theintensity of the received transmission radiation; c. a second receivingmeans, i. which is disposed on the body that at least partiallysurrounds said aerosol resting area, ii. which is disposed in relationto said transmitting means so as to primarily receive scatteredradiation, and iii. which emits a second analysis signal thatcorresponds to the intensity of the received scattered radiation; and d.a control means, to which the first and second output signals aresupplied and which analyses the first and second output signals in orderto determine the parameters of an aerosol in said aerosol resting area.2. A device for detecting the parameters of an aerosol according toclaim 1, wherein the transmitting means emits the radiation through afirst translucent wall section of the body surrounding the aerosolresting area.
 3. A device for detecting the parameters of an aerosolaccording to claim 1, wherein the first receiving means receives thetransmission radiation through a second wall section of the bodysurrounding the aerosol resting area.
 4. A device for detecting theparameters of an aerosol according to claim 1, wherein the secondreceiving means receives the scattered radiation through a third wallsection of the body surrounding the aerosol resting area.
 5. A devicefor detecting the parameters of an aerosol according to claim 1, whereinthe body surrounding the aerosol resting area is made of a translucentmaterial.
 6. A device for detecting the parameters of an aerosolaccording to claim 1, wherein the body surrounding the aerosol restingarea is made of a transparent material and the transmitting means isprovided with a surface made of a translucent material, through whichradiation is emitted.
 7. A device for detecting the parameters of anaerosol according to claim 1, wherein the first receiving means isprovided with a surface made of a translucent material, through whichthe radiation is received.
 8. A device for detecting the parameters ofan aerosol according to claim 1, wherein the second receiving means isprovided with a surface made of a translucent material, through whichthe radiation is received.
 9. A device for detecting the parameters ofan aerosol according to claim 1, wherein the control means activates thetransmitting means to emit the radiation into the aerosol resting area.10. A device for detecting the parameters of an aerosol according toclaim 9, wherein the control means activates the transmitting means suchthat first time periods, in which the transmitting means emits radiationinto the aerosol resting area, alternate with second time periods, inwhich the transmitting means does not emit radiation into the aerosolresting area.
 11. A device for detecting the parameters of an aerosolaccording to claim 9, wherein in the second time periods, the controlmeans determines the proportion of ambient light in the output signalsof the first and/or second receiving means.
 12. A device for detectingthe parameters of an aerosol according to claim 11, wherein the controlmeans makes use of the proportion of ambient light when analysing theoutput signals of the first and second receiving means.
 13. A device fordetecting the parameters of an aerosol according to claim 12, whereinthe control means forms the difference of the output signal of the firstreceiving means and the first ambient light proportion and/or thedifference of the output signal of the second receiving means and thesecond ambient light proportion.
 14. A device for detecting theparameters of an aerosol according to claim 13, wherein the controlmeans forms the quotient from the difference of the output signal of thesecond receiving means and the second ambient light proportion and thedifference of the output signal of the first receiving means and thefirst ambient light proportion.
 15. A device for detecting theparameters of an aerosol according to claim 1, wherein the control meansforms the quotient from the output signal of the second receiving meansand the output signal of the first receiving means.
 16. A device fordetecting the parameters of an aerosol, according to claim 1, whereinthe radiation emitted by the transmitting means is light, in particularinfrared light.
 17. Inhalation therapy device having a device fordetecting the parameters of an aerosol according to claim 1, wherein thebody surrounding the aerosol resting area is a mouthpiece of theinhalation therapy device.
 18. Inhalation therapy device according toclaim 17, wherein a nebuliser nozzle or a membrane nebuliser isprovided.
 19. Inhalation therapy device according to claim 18, whereinthe control means is connected with a compressor for the nebulisernozzle or with an excitation device for the membrane nebuliser.